Failure Analysis Report - AFA Good Report {0374, 1000} Caterpillar


Failure Analysis Report - AFA Good Report {0374, 1000}

Usage:

D3400 01T


Engine
3054 and 3056
3200
3300
3400
3400 All, 3300 All, 3200 All, 3100 All, 3000 All, and D-series All
3500 and G3500 Engines
All 3600 Engines
All C280 Engines
All Marine Propulsion, Marine Auxiliary, and Marine Generator Sets
C-10 All
C-9 and C9 All
C11 All
C12 and C-12 All
C13 and C-13 All
C15 and C-15 All
C16 and C-16 All
C175 Engines
C18 and C-18 Engines
C27 Engines
C32 Engines
C4.4 Engines
C6.6
C7 All
C7.1

Introduction

This is an example of a good AFA report. Please review the notes that explain how each section of this report adequately communicates the information necessary for a proper failure analysis. (Notes are indicated by a box with bolded text at the beginning of each section.)

Table 1
Contains all expected information related to customer name, vessel name, serial number, engine hours, dealer work order number. 

Table 2
Customer: ABC Co. 
Date: March 14th, 2013  Failure Date: February 28th, 2013 
Failed Part Number: 317-1121 Lock nut, injector rocker arm.  Hours in Service: 761 
Engine Model: 3512C  Engine Serial Number: NJT00XXX 

Section 1

Table 3
Contains expected summary of complaint and high-level failure description. 

Parts Received:

Failure on Diesel Engine #1, powering ABC Co. locomotive #1359. Failed parts were removed and brought to dealer A for analysis.

Condition Upon Receipt:

Injector from cylinder #7 had broken into two main sections, the body and the solenoid.

Section 2

Table 4
Contains reasonable pertinent history, observations, and facts, including environmental and adjustment observations, SOS report results, pertinent historic maintenance practices, and well-articulated findings of failed parts. Timeline builds story of what failed first. High-quality pictures of pertinent related components with reasonable observations included in subsequent pages. 

Facts:

The engine cylinder #7 was not functioning. The cylinder #7 valve cover had a hole, which was punched out from the inside. There was fuel and engine oil on the floor, walls, and ceiling of the locomotive engine room. The engine oil level was overfull due to fuel contamination. An oil analysis reported 19.44% fuel dilution of the engine oil. There was a higher than average metal particle count in the oil filter media. Removal of the valve cover revealed the cylinder #7 injector was severely damaged. The injector hold-down bolt had broken, allowing the injector to lose its seating ability. Only the injector rocker arm kept the injector from escaping through the valve cover. The injector from cylinder #7 had broken into two main sections, the body and the solenoid. The injector solenoid was badly hammered and rounded from bouncing around under the valve cover. Eventually, the solenoid punched a hole in the valve cover.

The valve cover was also damaged inside from the injector rocker arm adjustment screw, which had turned to reach its highest point possible. The adjustment screw locknut was found to be loose, which allowed the adjustment screw to turn freely, and slowly work its way higher and higher. As the adjustment screw was backing out, this caused more clearance between the injector rocker arm and its injector. The injector hold-down bolt could not tolerate the additional and continuous stresses, first the head of the bolt broke off, and then the bolt broke again in the threaded area. The head of the bolt broke off due to a stress-related fatigue fracture. The broken threaded area of the bolt was a ductile fracture. Both of these bolt fractures indicate high stress. Since the injector was now free to continuously rebound in its bore, damage to the injector body and bore of the cylinder head were inevitable. The injector bore of the cylinder head was pounded and damaged. The #7 cylinder head must be replaced.

The 11 remaining valve covers were removed to verify the valve lash and injector adjustments. The 0.044” valve lash measured on the exhaust valve from cylinder #10, slightly exceeded Caterpillar’s 0.040” +/- 0.003” specification. All the injector height adjustments on the remaining 11 cylinders were within tolerances. The torque of the 11 remaining locknuts for the injector rocker arm adjusting screws was validated. The locknut on injector rocker arm #12 was torqued to 79 lb/ft, which is 10 lb/ft under the 89 lb/ft spec, but within the minimum +/- 11 lb/ft tolerance.

The ABC Co. maintenance division had verified the valve lash and injector adjustments in February 2013, during the 250-500 hour inspection. On the ABC Co. completed form titled “Inspection 250-500 hrs, employee # 179923 performed the “inspect/adjust” of the valve lash and injector height. The technician signed and dated the form Feb.13th, 2013. There was no indication on the form whether the valve lashes and injectors were readjusted or not. It is not necessary to loosen the injector rocker arm locknut if the injector height is only being validated, this locknut is loosened only if the injector height is readjusted.

Oil sample taken from this engine on Feb. 5th, 2013 showed normal wear, and no unusual amounts of metal particles in the oil. On July 19th, 2011, Bill’s Service Corp. (third-party service provider) checked all valve lashes and injector heights, then readjusted them back to Caterpillar’s exact specifications. The adjustment for injector #7 was found to be 64.46 mm, and was reset to 64.34 mm at that time. The injector’ adjustment screw locknut would have been loosened and then retorqued at that time.

Section 3

Table 5
Contains multiple possible root causes which are reasonable and based upon facts. 

List of Possible Root Causes of Failure

  1. The locknut of the #7 injector rocker arm adjustment screw was not torqued adequately during the ABC Co. valve lash and injector adjustment, completed two weeks earlier. Therefore, the adjustment screw changed positions and created excess rocker arm to injector clearance.

  2. The locknut on the #7 injector rocker arm adjustment screw was not sufficiently torqued by Bill’s Service Corp., during the valve lash and injector adjustments on July 19th, 2011. This locknut became loose and allowed the adjustment screw to change position and create excess rocker arm to injector clearance.

Section 4

Table 6
Proper summary of facts gathered articulate most likely root cause of failure. Additional steps/limiting information is also articulated. 

The Root Cause:

Utilizing the facts made available to Caterpillar, the clear cause of this failure was insufficient torque on the lock nut for the #7 injector rocker arm adjusting screw. The broken injector hold-down bolt, plus the failure of the #7 injector and the #7 cylinder head are collateral damage.

The root cause would be how this locknut became loose, at the time of this report, the root cause has not yet been determined. This is due to the limited information supplied to Caterpillar by the ABC Co. maintenance division, who confirmed that the valve lash and injector height had been verified, two weeks prior to the final failure.

If Bill’s Service Corp. had incorrectly torqued the locknut for the #7 injector rocker arm adjustment screw, the ABC Co. verification of the injector adjustments may have revealed this issue. If this injector height was adjusted by ABC Co., then the locknut in question was improperly torqued by the ABC Co. technician.

Further investigation is required.

Section 5

Table 7
Conclusion of root cause clearly stated. Dealer contact/reference information provided for further questions/requests. Summary of repairs included. 

Summary:

Additional photos available upon request.

Bill's Service Corp. readjusted the #7 injector height when the engine had 0-1 hour. This fact indicates that there was no manufacturer defect in material or workmanship involved in the root cause of failure.

Repair Process: Cylinder head replaced with new injector and properly torqued/adjusted.

Investigation Completed By:

Joe Marine
Cat Dealer
Technical Communicator

Photos



    Illustration 1g06098816

  1. Valve cover from cylinder # 7, ventilated by the injector solenoid. Red circle at the right of the photo shows where the locknut of the injector rocker arm adjustment screw contacted the valve cover, while backing out of the rocker arm.


    Illustration 2g06098819

  2. Valve cover removed, the injector was loose and injector solenoid was badly pounded. Locknut on injector rocker arm adjustment screw was loose, and this adjustment screw had backed out as high as could possibly go.


    Illustration 3g06098813

  3. Injector #7 and related parts.


    Illustration 4g06098835

  4. Injector #7 rocker arm, upper surface of adjustment screw locknut fretting inside the valve cover.


    Illustration 5g06098839

  5. Injector pushrod gouged out underside of the rocker arm after the adjustment screw backed out as far as possibly could.


    Illustration 6g06098866

  6. The loose injector damaged underside of injector rocker arm.


    Illustration 7g06098891

  7. Spalling on injector rocker arm foot, damaged after the adjustment screw backed out and the clearance between this foot and the injector became excessive.


    Illustration 8g06098894

  8. Broken injector #7 hold-down bolt with detached head, stress fatigue fracture.


    Illustration 9g06098898

  9. Head of injector hold-down bolt. The red arrows point to bolt some of the multiple ratchet marks which indicate high stress.


    Illustration 10g06098901

  10. Contact damage to cylinder head # 7, caused by the loose injector. The remaining threaded section of injector hold-down bolt still in the head.

Caterpillar Information System:

A New Cylinder Liner Assembly And Piston Is Now Used For Certain 3516 Locomotive Engines {1201, 1216} A New Cylinder Liner Assembly And Piston Is Now Used For Certain 3516 Locomotive Engines {1201, 1216}
HPU300 Hydraulic Power Pack Hydraulic Oil Filter - Replace
C4.4 and C6.6 Engines Diagnostic Trouble Codes
ECPC Valves May Fail on Cat Transmission Systems {3073, 3139, 3167} ECPC Valves May Fail on Cat Transmission Systems {3073, 3139, 3167}
349F and 352F Excavators Machine System Specifications Swing Drive - Left Swing Drive and Right Swing Drive
C175-16 and C175-20 Locomotive Engines Fuel Pump (High Pressure) - Remove and Install
C175-16 and C175-20 Locomotive Engines Air Inlet Manifold - Remove and Install
Front Suspension Failures May Occur on Certain 777D/777F/777G Off-Highway Trucks {7200, 7201, 7551} Front Suspension Failures May Occur on Certain 777D/777F/777G Off-Highway Trucks {7200, 7201, 7551}
C175-16 and C175-20 Locomotive Engines Valve Lifter - Install
C175 Tier 4 Final Engines for Off-Highway Trucks DEF Pressure Does Not Respond
M0074040: 509-5085 Lifting Tool Assembly {0374, 0599, 0629, 0632, 3023, 3159, 3160, 5363, 7000} M0074040: 509-5085 Lifting Tool Assembly {0374, 0599, 0629, 0632, 3023, 3159, 3160, 5363, 7000}
C12.9 Marine Engines Crankshaft Front Seal - Remove and Install
C4.4 and C6.6 Engines General Information
C4.4 and C6.6 Engines Welding Precaution
C4.4 and C6.6 Engines Component Location
PM820, PM822, and PM825 Cold Planer Machine Systems Conveyor Belt (Second Stage) - Remove and Install
G3512 Generator Set Engines Manifold Air Pressure Sensor
G3512 Generator Set Engines Measuring Inlet Manifold Temperature
G3512 Generator Set Engines Restriction of Air Inlet and Exhaust
HPU300 Hydraulic Power Pack Before Starting Motor
G3612 and G3616 Engines Maintenance Interval Schedule - Engines With 10.5 or 11.1 Compression Ratio and Use Natural Gas
G3612 and G3616 Engines Maintenance Interval Schedule - Bio-Gas Engines
G3612 and G3616 Engines Maintenance Interval Schedule - Engines with a 9.2:1 Compression Ratio and Use Wellhead or Natural Gas
<SUP>&reg;</SUP> Marine Display Connections
Back to top
The names Caterpillar, John Deere, JD, JCB, Hyundai or any other original equipment manufacturers are registered trademarks of the respective original equipment manufacturers. All names, descriptions, numbers and symbols are used for reference purposes only.
CH-Part.com is in no way associated with any of the manufacturers we have listed. All manufacturer's names and descriptions are for reference only.